Singapore teens are just not active enough and this could lead to health problems when they become adults, a National Institute of Education (NIE) study has found.
It involved 244 students from seven secondary schools, who wore motion sensors on their hips for five days, two of which were at the weekend.
It was found that the number of steps the students took was 16 per cent higher in school than outside on the weekdays, and that boys were more active than girls.
But not one of the students met the national guideline of having at least an hour of moderate to vigorous physical activity a day. A brisk walk which raises the heart rate to 140 beats a minute would count as moderate activity.
The sedentary lifestyle could have a negative impact on the health of some of the students.
Blood tests were carried out on 229 participants, and the results showed that close to 12 per cent were at risk of metabolic syndrome. This covers a series of conditions, including increased blood pressure, a high blood sugar level, excess fat around the waist and abnormal cholesterol levels, which occur together.
The syndrome increases the risk of heart disease, stroke and diabetes when adulthood is reached.
Professor Michael Chia, who led the study, said what was significant was how nearly half of the 12 per cent were of normal weight and even underweight.
For these cases, the syndrome was not caused by any underlying weight issues, but likely by their "sedentary lifestyle", explained Prof Chia, an expert on physical education and paediatric exercise physiology with the NIE, calling it a worrying trend.
"The findings clearly show that our youth are not sufficiently engaged in physical activity," said the 51-year-old, who conducted the study with colleagues Swarup Mukherjee and Jamie Lye. "If this behaviour becomes entrenched, it may have dire consequences on the future physical and metabolic health of adult Singaporeans."
He applauded the Ministry of Education's recent move to increase physical education time, from one to two hours a week in secondary schools. But he stressed that more needs to be done to get children moving. One suggestion is to have five-minute breaks between lessons. Another is extending recess time so that students have time for games.
There was also a need to get girls more engaged in sport.
He noted that NIE was already trying these measures in some schools and studying their impact, such as whether having a longer recess leads to a drop in students' performances in tests.
Secondary students told about Prof Chia's findings said they were not surprised. A typical comment came from April Lim, 16, who will enter Ngee Ann Polytechnic this year to study business.
"I don't mind sports like netball, but I just don't have the time. My typical school day consists of lessons, CCA - the IT club in my case - then tuition and homework," she said. "On weekends, I play computer games and watch my favourite TV shows, and movies on my laptop."
Business manager R. Arun, 40, who has two school-going children, said the findings were cause for concern. "I see kids, mine included, glued to their phones and the computer. I think both parents and schools should do something about this," he said.